This invention relates to polymeric organosiloxane ammonium salts, which include a silica-like skeleton, of oxo acids of the elements vanadium, niobium, tantalum, molybdenum and tungsten. The term "oxo acids" as used in this application represents simple oxo acids, isopolyoxo acids and heteropolyoxo acids. Furthermore, in accordance with this invention, one or several oxo groups may be replaced by peroxo groups. This invention also relates to the preparation of these salts, as well as the use of the salts as catalysts for oxidation reactions, especially reactions using hydrogen peroxide as the oxidizing agent.
Polymeric organosiloxane ammonium salts with silica-like skeletons have been described in German Patent No. 31 20 195. This patent is entirely incorporated herein by reference. A further development of the salts described in this German patent relate to macroscopically spherical particles with specific properties, as disclosed in German Patent No. 38 00 564, which patent also is entirely incorporated herein by reference. The macroscopically spherical, polymeric, tertiary or secondary organosiloxane amine compounds which form the base for the salts of German Patent No. 38 00 564 can be transferred into salts by means of quaternization with, for example, alkyl halogenides, or by means of reaction with a protonic acid, as described in German Patent No. 38 00 563. This German patent also is completely incorporated herein by reference.
The polymeric salts of German Patent No. 31 20 195 and German Patent No. 38 00 564 include units of formula (III) ##STR3## in which R.sup.1 and R.sup.2 are identical or different and signify a group of formula (II): ##STR4## The nitrogen atoms in Formula (III) are connected via the R.sup.5 groups to the silicon atoms in Formula (II), and R.sup.5 represents an alkylene group with 1 to 10 carbon atoms, a cycloalkylene group with 5 to 8 carbon atoms or a unit of one of the following formulae: ##STR5## wherein n is a number from 1 to 6 and indicates the number of methylene groups in the nitrogen position; m is a number from 0 to 6; the free valences of the oxygen atoms bound to the silicon atom are saturated as in silica skeletons by silicon atoms of further groups corresponding to formula (II) and/or with the metal atoms of one or several of the cross-linking bridge-type cross links ##STR6## in which M is a silicon, titanium or zirconium atom and R' is a linear or branched alkyl group with 1 to 5 carbon atoms; the ratio of the silicon atoms from the groups of formula (II) to the metal atoms in the bridge-type cross links is 1:0 to 1:10; in which R.sup.3 is equal to R.sup.1 or R.sup.2 or hydrogen, a linear or branched alkyl group of 1 to 20 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a benzyl group; R.sup.4 represents hydrogen, a linear or branched alkyl group with 1 to 20 carbon atoms or a cycloalkyl, benzyl, allyl, propargyl, chloroethyl, hydroxyethyl, or chloropropyl group having 5 to 8 carbon atoms; and Y is an anion with the valence of y equal to 1 to 3 selected from the group of halogenide, hypochlorite, sulfate, hydrogen sulfate, nitrite, nitrate, phosphate, dihydrogen phosphate, hydrogen phosphate, carbonate, hydrogen carbonate, hydroxide, chlorate, perchlorate, chromate, dichromate, cyanide, cyanate, rhodanide, sulfide, hydrogen sulfide, selenide, telluride, borate, metaborate, azide, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, formate, acetate, propionate, oxalate, trifluoroacetate, trichloroacetate or benzoate.
It is also known from the above mentioned German patents that the Y anion can be exchanged in polymeric salts of Formula (III) by means of a static or dynamic ion exchange with another anion from the above-named series.
These German patents indicate that the polymeric organosiloxane ammonium salts are used as ion exchangers, absorbers, catalytic carriers and active-substance carriers. No information is included in these German patents concerning the selection of the X anion for use in definite reactions which are carried out in the presence of heterogeneous catalysts.
It is known that oxidation reactions using peroxo compounds, especially hydrogen peroxide, can be catalyzed by means of oxo compounds of, for example, molybdenum, tungsten and vanadium. The intermediary formation of peroxo acids of Mo, W and V is considered as an essential step. Among the oxidation reactions catalyzed in this manner, the following reactions can be named as examples: Olefin epoxidation; olefin hydroxylation; olefin splitting; oxime formation from ketones with ammonia and hydrogen peroxide; sulfenamide formation from a thiol, an amine and hydrogen peroxide as well as the oxidation of thiols to higher-oxidized sulfur compounds, cf. the brochure of the firm Peroxid-Chemie GmbH "H.sub.2 O.sub.2 in der organischen Synthese" (which translates to: "H.sub.2 O.sub.2 in Organic Synthesis") A 0.1.2.dlD-381, which is entirely incorporated herein by reference. One disadvantage of using the abovedescribed catalysts is the fact that the recovery of the dissolved catalysts is technically expensive, and therefore, the economy of the oxidation reactions is frequently questionable. Practically speaking, the use of, for example, molybdate-charged ion exchangers or tungstate-charged ion exchangers based on organic polymers does not constitute a satisfactory solution because of the generally insufficient thermal, mechanical and chemical stability.